Light emitting device

ABSTRACT

A light emitting device includes a base member; a light emitting element mounted on the base member; a light-transmissive member that covers an upper surface of the light emitting element, and is substantially rectangular in a plan view; and a light reflecting member that covers a lateral surface of the light-transmissive member, the light reflecting member having a substantially rectangular frame shape in a plan view. A width of the light reflecting member is smaller along a short side of the light-transmissive member than along a long side of the light-transmissive member. A height of the light reflecting member is smaller along the short side of the light-transmissive member than along the long side of the light-transmissive member at a position separated from an outer edge of the light reflecting member by a predetermined distance.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No.2015-145788, filed on Jul. 23, 2015, the disclosure of which is herebyincorporated by reference in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a light emitting device and a methodof manufacturing the same.

2. Description of Related Art

Semiconductor light emitting elements such as light emitting diodes(LEDs) and laser diodes (LDs) are used as various kinds of lightsources. Particularly in recent years, as illumination light sourcesreplacing fluorescent lamps, light emitting diodes are receivingattention as next-generation lighting, due to their small powerconsumption and long life. Still, further improvements in light emissionoutput and in light emission efficiency are needed for the lightemitting diodes. For example in the field of light sources includingvehicular headlights and projector lighting, there is also a need forlight sources that exhibit high luminance and have a particular lightdistribution, e.g., a hemispherical light distribution calledLambertian. There has been proposed a light emitting device in whichlateral surfaces of a light emitting element are covered with a lightreflecting member for the purpose of attaining high front luminance.Light emitting devices are required to maintain their performance over along period of use, particularly in interior and exterior illuminationof vehicular applications.

As such, a light emitting device has been described in which lateralsurfaces of a light emitting element is covered with a light reflectingmember. For example, Japanese Unexamined Patent Application PublicationNo. 2009-218274 discloses a semiconductor light emitting device thatincludes: a light emitting element; a wavelength conversion layerpositioned on or above the light emitting element; a reflecting memberdisposed adjacent to a lateral surface of the wavelength conversionlayer and to a lateral surface of the light emitting element, thelateral surface of the light emitting element being positioned on anidentical surface side to the lateral surface of the wavelengthconversion layer; and a base member on which the light emitting elementand the reflecting member are mounted. The light emitting device has astructure in which the lateral surface of the wavelength conversionlayer (e.g., a light-transmissive member) and the lateral surface of thelight emitting element are covered with the reflecting member (e.g., alight reflecting member) formed to surround the wavelength conversionlayer.

Further, Japanese Unexamined Patent Application Publication No.2012-79840 discloses a light emitting device that includes: a basemember; at least one light emitting element mounted on the base member;a resin layer disposed on the light emitting element; a plate-likemember mounted on the resin layer; and a reflecting resin memberprovided to surround the resin layer and the plate-like member. Thereflecting resin member covers the entire lateral surface of theplate-like member. The light emitting device has a structure in whichthe lateral surface of the resin layer (i.e., the light-transmissivemember) and the lateral surface of the plate-like member are coveredwith the reflecting resin member (i.e., the light reflecting member)formed to surround the resin layer.

With the light emitting devices disclosed in Japanese Unexamined PatentApplication Publication No. 2009-218274 and 2012-79840, the reflectingmember at the lateral surface of the light emitting element maydeteriorate over a long period of use.

SUMMARY

An objective of an embodiment of the present disclosure is to provide alight emitting device including a light reflecting member lesssusceptible to deterioration and a method of manufacturing the same.

A light emitting device according to an embodiment of the presentdisclosure includes: a base member; a light emitting element mounted onthe base member; a light-transmissive member that covers an uppersurface of the light emitting element and is substantially rectangularin a plan view; and a light reflecting member that covers a lateralsurface of the light-transmissive member and has a substantiallyrectangular frame shape in a plan view. A width of the light reflectingmember is smaller along a short side of the light-transmissive memberthan along a long side of the light-transmissive member. A height of thelight reflecting member is smaller along the short side of thelight-transmissive member than along the long side of thelight-transmissive member at a position separated from an outer edge ofthe light reflecting member by a predetermined distance.

A light emitting device according to an embodiment of the presentdisclosure includes: a base member; a light emitting element mounted onthe base member; a light-transmissive member that covers an uppersurface of the light emitting element and is substantially rectangularin a plan view; and a light reflecting member that includes a frame bodyformed to surround the light-transmissive member and a filling memberprovided between the frame body and the light-transmissive member tocover a lateral surface of the light-transmissive member, the lightreflecting member having a substantially rectangular frame shape in aplan view. In the light emitting device, a width of the light reflectingmember is smaller along a short side of the light-transmissive memberthan along a long side of the light-transmissive member, and a height ofthe frame body is smaller along the short side of the light-transmissivemember than along the long side of the light-transmissive member.

A method of manufacturing a light emitting device according to anembodiment of the present disclosure includes: forming alight-transmissive member being substantially rectangular in a plan viewto cover an upper surface of a light emitting element mounted on a basemember; and forming a light reflecting member in a substantiallyrectangular frame shape in a plan view, the forming the light reflectingmember including forming the frame body to surround thelight-transmissive member and forming a filling member between the framebody and the light-transmissive member to cover a lateral surface of thelight-transmissive member. In the forming the light reflecting member,the light reflecting member is formed such that a width of the lightreflecting member is smaller along a short side of thelight-transmissive member than along a long side of thelight-transmissive member, and in the forming the frame body, the framebody is formed such that a height of the frame body is smaller along theshort side of the light-transmissive member than along the long side ofthe light-transmissive member.

With the light emitting device according to the embodiment of thepresent disclosure, the light reflecting member is less susceptible todeterioration. Further, with the method of manufacturing a lightemitting device according to the embodiment of the present disclosure, alight emitting device including a light reflecting member lesssusceptible to deterioration can be manufactured.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view schematically showing the structure of alight emitting device according to an embodiment.

FIG. 2 is a plan view schematically showing the structure of the lightemitting device according to the embodiment.

FIG. 3 is a cross-sectional view schematically showing the structure ofthe light emitting device according to the embodiment, showing a crosssection taken along line in FIG. 2.

FIG. 4 is a cross-sectional view schematically showing the structure ofthe light emitting device according to the embodiment, showing a crosssection taken along line IV-IV in FIG. 2.

FIG. 5A is a plan view schematically showing a base member preparationstep in a method of manufacturing the light emitting device according tothe embodiment.

FIG. 5B is a cross-sectional view schematically showing the base memberpreparation step in the method of manufacturing the light emittingdevice according to the embodiment, showing a cross section taken alongline VB-VB in FIG. 5A.

FIG. 5C is a cross-sectional view schematically showing the base memberpreparation step in the method of manufacturing the light emittingdevice according to the embodiment, showing a cross section taken alongline VC-VC in FIG. 5A.

FIG. 6A is a plan view schematically showing a light emitting elementsmounting step in the method of manufacturing the light emitting deviceaccording to the embodiment.

FIG. 6B is a cross-sectional view schematically showing the lightemitting elements mounting step in the method of manufacturing the lightemitting device according to the embodiment, showing a cross sectiontaken along line VIB-VIB in FIG. 6A.

FIG. 6C is a cross-sectional view schematically showing the lightemitting elements mounting step in the method of manufacturing the lightemitting device according to the embodiment, showing a cross sectiontaken along line VIC-VIC in FIG. 6A.

FIG. 7A is a plan view schematically showing a light-transmissive memberforming step in the method of manufacturing the light emitting deviceaccording to the embodiment.

FIG. 7B is a cross-sectional view schematically showing thelight-transmissive member forming step in the method of manufacturingthe light emitting device according to the embodiment, showing a crosssection taken along line VIIB-VIIB in FIG. 7A.

FIG. 7C is a cross-sectional view schematically showing thelight-transmissive member forming step in the method of manufacturingthe light emitting device according to the embodiment, showing a crosssection taken along line VIIC-VIIC in FIG. 7A.

FIG. 8A is a plan view schematically showing a frame body forming stepin the method of manufacturing the light emitting device according tothe embodiment.

FIG. 8B is a cross-sectional view schematically showing the frame bodyforming step in the method of manufacturing the light emitting deviceaccording to the embodiment, showing a cross section taken along lineVIIIB-VIIIB in FIG. 8A.

FIG. 8C is a cross-sectional view schematically showing the frame bodyforming step in the method of manufacturing the light emitting deviceaccording to the embodiment, showing a cross section taken along lineVIIIC-VIIIC in FIG. 8A.

FIG. 9A is a plan view schematically showing a filling member formingstep in the method of manufacturing the light emitting device accordingto the embodiment.

FIG. 9B is a cross-sectional view schematically showing the fillingmember forming step in the method of manufacturing the light emittingdevice according to the embodiment, showing a cross section taken alongline IXB-IXB in FIG. 9A.

FIG. 9C is a cross-sectional view schematically showing the fillingmember forming step in the method of manufacturing the light emittingdevice according to the embodiment, showing a cross section taken alongline IXC-IXC in FIG. 9A.

FIG. 10A is a plan view schematically showing a light reflectingmaterial curing step in the method of manufacturing the light emittingdevice according to the embodiment.

FIG. 10B is a cross-sectional view schematically showing the lightreflecting material curing step in the method of manufacturing the lightemitting device according to the embodiment, showing a cross sectiontaken along line XB-XB in FIG. 10A.

FIG. 10C is a cross-sectional view schematically showing the lightreflecting material curing step in the method of manufacturing the lightemitting device according to the embodiment, showing a cross sectiontaken along line XC-XC in FIG. 10A.

FIG. 11 is a schematic cross-sectional view for illustrating a method offorming the frame body in two stages in the step of forming the framebody of the light emitting device according to the embodiment, being anenlarged partial cross-sectional view taken along line VIIIB-VIIIB inFIG. 8A.

DETAILED DESCRIPTION

In the following, a description will be given of an embodiment withreference to the drawings. Note that, the following embodiment is merelyan illustration of a light emitting device for embodying the technicalidea of the present embodiment, and is not intended to be limiting.Further, the size, material, shape, relative disposition and the like ofmembers described in the embodiment are merely illustrative and notintended to limit the scope of the present invention thereto unlessotherwise specified. The size, positional relationship and the like ofmembers shown in the drawings may be exaggerated for the sake ofclarity.

Further, in a light emitting device according to the embodiment,“upper/top”, “lower/bottom”, “right”, “left” and the like are replacedby one another depending on the situation. In the present specification,“upper/top”, “lower/bottom”, and the like refer to the relative positionamong members in the drawings referred to for description, and are notintended to specify the absolute position unless otherwise specified.

(Light Emitting Device)

First, a description will be given of a light emitting device accordingto the present embodiment.

FIG. 1 is a perspective view schematically showing the structure of thelight emitting device according to the embodiment. FIG. 2 is a plan viewschematically showing the structure of the light emitting deviceaccording to the embodiment. FIG. 3 is a cross-sectional viewschematically showing the structure of the light emitting deviceaccording to the embodiment, showing a cross section taken along line inFIG. 2. FIG. 4 is a cross-sectional view schematically showing thestructure of the light emitting device according to the embodiment,showing a cross section taken along line IV-IV in FIG. 2.

A frame body 5 a and a filling member 5 b, which are actually integratedas shown in FIG. 2, are shown in FIGS. 3 and 4 with a broken linebetween them for the sake of convenience, so that the boundary betweenthe frame body 5 a and filling member 5 b can be recognized. The sameholds true for FIGS. 10B and 10C which will be referred to later.

The light emitting device 10 mainly includes a base member 1,electrically conductive patterns 2 a, 2 b, and 2 c, light emittingelements 3, a light-transmissive member 4, and a light reflecting member5.

(Base Member)

The base member 1 may be made of an insulating member such as glassepoxy, resin, or ceramic, or alternatively the base member 1 may be ametal member provided with an insulating film at its surface. Inparticular, the base member 1 is preferably made of ceramic, which ishighly heat-resistant and environment-resistant. Exemplary ceramicmaterials include alumina, aluminum nitride, mullite and the like.

(Electrically Conductive Patterns)

At the surface of the base member 1, the electrically conductivepatterns 2 a and 2 b being a pair of positive and negative electrodesare provided. The electrically conductive patterns 2 a and 2 b arerespectively provided with through holes 6 a and 6 b where the basemember 1 is exposed. The electrically conductive relaying patterns 2 care provided between the electrically conductive patterns 2 a and 2 b inorder to relaying thereof (see FIG. 5A). The through holes 6 a and 6 beach have an elongated shape extending in a direction along the longside of the light-transmissive member 4. That is, the through holes 6 aand 6 b in the present embodiment each have an elongated shape in thelongitudinal direction of the base member 1, and are partially coveredwith the light reflecting member 5. In the through holes 6 a and 6 b,the surface of the base member 1 and the light reflecting member 5 arein contact with each other.

The electrically conductive patterns 2 a, 2 b, and 2 c may be formed bymetal such as copper, aluminum, gold, silver, platinum, titanium,tungsten, palladium, iron, and nickel, or alloy containing any of theforegoing metals, but the material for forming the electricallyconductive patterns 2 a, 2 b, and 2 c is not limited thereto. Further,the uppermost surfaces of the electrically conductive patterns 2 a, 2 b,and 2 c formed at the upper surface of the base member 1 are preferablycovered with a material exhibiting high reflectivity such as silver orgold, in order for light from the light emitting elements 3 to beefficiently extracted. Such electrically conductive patterns 2 a, 2 b,and 2 c can be formed by electroplating, electroless plating, vapordeposition, sputtering and the like. For example, when Au bumps are usedfor mounting the light emitting elements 3, employing Au for theuppermost surfaces of the electrically conductive patterns 2 a, 2 b, and2 c improves joining.

By having the electrically conductive patterns 2 a and 2 b, the heatreleasing property of the light emitting device 10 improves. Also, byvirtue of the electrically conductive patterns 2 a and 2 b having thethrough holes 6 a and 6 b, adhesion between the light reflecting member5 and the base member 1 improves because the light reflecting member 5is in contact with the base member 1 at the sites of the electricallyconductive patterns 2 a and 2 b. Further, the shape of the through holes6 a and 6 b being elongated in the extending direction of theelectrically conductive patterns aids current to smoothly flow throughthe electrically conductive patterns 2 a and 2 b, and increases theadhesion area between the base member 1 and the light reflecting member5.

(Light Emitting Elements)

In the present embodiment, three light emitting elements 3 are mountedon the base member 1. In the present embodiment, the light emittingelements 3 each have a pair of positive and negative electrodes on anidentical surface. The pairs of electrodes are flip-chip mounted on theelectrically conductive patterns 2 a, 2 b, and 2 c on the surface of thebase member 1 via bumps 8 a made of Au or the like. The upper surfacesof the light emitting elements 3, which are opposite to the lowersurfaces provided with the electrodes, are the main light outputsurfaces.

The light emitting elements 3 are preferably light emitting diodes. Thelight emitting elements 3 may be of any wavelength. For example, thematerial of blue, green-color light emitting elements 3 may be a ZnSe ornitride-based semiconductor (In_(X)Al_(Y)Ga_(1-X-Y)N, 0≦X, 0≦Y, X+Y<1),or GaP. Further, the material of red light emitting elements 3 may beGaAlAs, AlInGaP or the like. Still further, semiconductor light emittingelements made of other materials may be used. The composition, emissionlight color, size, number and the like of the light emitting elements 3may be selected as appropriate depending on the intended use.

The light emitting elements 3 are, for example, each obtained by havinga nitride semiconductor layer stacked on a light-transmissive sapphiresubstrate for crystal growth. The sapphire substrate is the uppersurface of each light emitting element 3, and serves as the main lightoutput surface. Note that, the growth substrate may be removed, forexample, by polishing, LLO (Laser Lift Off) and the like. Such a growthsubstrate is not limited to a sapphire substrate, and can be changed asappropriate. For example, a GaN substrate may be employed.

(Light-Transmissive Member)

The light-transmissive member 4 is a member that covers the uppersurfaces of the light emitting elements 3. In the present embodiment,the light-transmissive member 4 has a plate-like, and provided on theupper surfaces of the three light emitting elements 3. Thelight-transmissive member 4 is formed to be substantially rectangular ina plan view. Further, in the present embodiment, the plate-likelight-transmissive member 4 is provided on the upper surfaces of thelight emitting elements 3, and therefore the lateral surfaces of thelight emitting elements 3 are not covered with the light-transmissivemember 4 at the periphery of the light-transmissive member 4.

The light-transmissive member 4 has a lower surface where the light fromthe light emitting elements 3 is input and an upper surface (i.e., lightemitting surface 4 a) where the light from the light emitting elements 3is output. The light-transmissive member 4 has a plate-like shape, withwhich the light reflecting member 5 covering lateral surfaces of thelight-transmissive member 4 hinders to creeps up onto the upper surfaceof the light transmissive member 4. The upper surface and lower surfaceof the light-transmissive member 4 are flat surfaces being substantiallyparallel to each other.

The light-transmissive member 4 is made of a material capable oftransmitting light having been emitted from the light emitting elements3 to the outside, and may contain a light diffusing member or afluorescent material that is capable of converting the wavelength of atleast part of the input light. Specifically, for example, thelight-transmissive member 4 may be a cut piece of a fluorescent materialingot such as a single crystal or polycrystalline fluorescent materialor a sintered body of fluorescent material powder, or may be a sinteredcomponent of a mixture of fluorescent material powder and resin, glass,an inorganic material or the like. While the thickness of thelight-transmissive member 4 is not particularly limited and can bechanged as appropriate, an exemplary thickness is about 50 μm to 300 μm.

The fluorescent material contained in the light-transmissive member 4should be capable of being excited by light emitted from the lightemitting elements 3. For example, a fluorescent material that can beexcited by a blue-color light emitting element or an ultraviolet lightemitting element may be: a cerium-activatedyttrium-aluminum-garnet-based fluorescent material (Ce:YAG); acerium-activated lutetium-aluminum-garnet-based fluorescent material(Ce:LAG); an europium and/or chromium-activated nitrogen-containingcalcium aluminosilicate based fluorescent material (CaO—Al₂O₃—SiO₂); aneuropium-activated silicate-based fluorescent material ((Sr,Ba)₂SiO₄); anitride-based fluorescent material such as a β-sialon fluorescentmaterial, a CASN-based fluorescent material, and a SCASN-basedfluorescent material; a KSF-based fluorescent material (K₂SiF₆:Mn); asulfide-based fluorescent material, a quantum dot fluorescent materialand the like. By combining the fluorescent materials and a blue-colorlight emitting element or an ultraviolet light emitting element, manycolors and color temperatures can be realized. For example, in certainembodiments of the present invention, light emitting devices can bemanufactured to emit light of various colors, including, for instance,white-color-based light. To obtain the light emitting device 10 thatemits white-color light, the type and concentration of the fluorescentmaterial contained in the light-transmissive member 4 are adjusted torender white color. The concentration of the fluorescent material is,for example, in a range of about 5% by mass to about 50% by mass.

The exemplary light diffusing members that can be contained in thelight-transmissive member 4 include titanium oxide, barium titanate,aluminum oxide, silicon oxide and the like.

(Light Reflecting Member)

The light reflecting member 5 is formed to surround thelight-transmissive member 4, and has a substantially rectangular frameshape in a plan view. In the present embodiment, the light reflectingmember 5 covers the lateral surfaces of the light-transmissive member 4and the lateral surfaces of the light emitting elements 3 not coveredwith the light-transmissive member 4.

The width of the light reflecting member 5 is smaller along the shortside of the light-transmissive member 4 than along the long side of thelight-transmissive member 4. Here, the short side of thelight-transmissive member 4 refers to both the right and left sides inFIG. 2, and the long side of the light-transmissive member 4 refers toboth the top and bottom sides in FIG. 2.

Further, the width of the light reflecting member 5 refers to thedistance from the outer edge (side) of the light-transmissive member 4to the outer edge (side) of the light reflecting member 5 that isadjacent to that outer edge (side) of the light-transmissive member 4 ina plan view. That is, the light reflecting member 5 is shaped such that,in FIG. 2, a distance W1 from the left side of the light-transmissivemember 4 to the left side of the light reflecting member 5, and adistance W1 from the right side of the light-transmissive member 4 tothe right side of the light reflecting member 5 are smaller than adistance W2 from the upper side of the light-transmissive member 4 tothe upper side of the light reflecting member 5, and a distance W2 fromthe lower side of the light-transmissive member 4 to the lower side ofthe light reflecting member 5.

In general, a light reflecting member made of resin is prone todeteriorate during a long period of use of the light emitting device.For example, cracks may occur. Accordingly, the light emitting devicepreferably contains the light reflecting member by a reduced amount.However, when the width of the light reflecting member is uniformlynarrowed over the entire perimeter of the light reflecting member forthe purpose of reducing the amount of the light reflecting member, theadhesion area between the light reflecting member and the base member isreduced. Then, the light reflecting member may be easily separated fromthe base member by the stress applied between the light reflectingmember and the base member.

In the present embodiment, setting the width W1 of the light reflectingmember 5 to be smaller than the width W2 reduces the amount of the resinconstituting the light reflecting member 5, and the light reflectingmember 5 is less likely to deteriorate. Further, it also suppressesoccurrence of separation at the interface between the light reflectingmember 5 and the base member 1, the interface between the lightreflecting member 5 and the light-transmissive member 4, and theinterface between the light reflecting member 5 and the members nearby.Thus, the light emitting device 10 possesses improved long-periodthermal shock resistance.

Further, at a position separated from the outer edge of the lightreflecting member 5 by a predetermined distance, the height of the lightreflecting member 5 is smaller along the short side of thelight-transmissive member 4 than along the long side of thelight-transmissive member 4. Here, the position separated from the outeredge of the light reflecting member 5 by a predetermined distance is,for example, the center position in the width of the frame body 5 a,which extends perpendicularly from the outer edge of the lightreflecting member 5. That is, it may be the position where the height ofthe frame body 5 a is at the maximum.

The light reflecting member 5 is made up of the frame body 5 a and thefilling member 5 b. In the present embodiment, the frame body 5 a andthe filling member 5 b integrally form the light reflecting member 5.Here, being integral refers to the state where, at the boundary of theframe body 5 a and the filling member 5 b, the light reflecting material(resin) of the frame body 5 a and the light reflecting material (resin)of the filling member 5 b so closely attach to each other that theboundary is hardly recognizable.

The frame body 5 a is formed to surround the light-transmissive member4. In the present embodiment, the frame body 5 a is formed to berectangular frame shape in a plan view, having its short sidesparalleled to the short sides of the light-transmissive member 4 and itslong sides paralleled to the long sides of the light-transmissive member4.

The filling member 5 b is provided between the frame body 5 a and thelight-transmissive member 4, and between the frame body 5 a and thelight emitting elements 3. The filling member 5 b covers the lateralsurfaces of the light-transmissive member 4 and the lateral surfaces ofthe light emitting elements 3.

The height of the frame body 5 a is smaller along the short side of thelight-transmissive member 4 than along the long side of thelight-transmissive member 4. Here, the height of the frame body 5 arefers to the distance from the upper surface of the base member 1 tothe upper end (uppermost surface) of the frame body 5 a. That is, asshown in FIGS. 3 and 4, the light reflecting member 5 is formed suchthat, a distance T1 from the base member 1 to the upper end of the framebody 5 a along the short side of the light-transmissive member 4 issmaller than a distance T2 from the base member 1 to the upper end ofthe frame body 5 a along the long side of the light-transmissive member4.

Setting the height of the frame body 5 a as above moderates creeping upof the filling member 5 b onto the light emitting surface 4 a along theshort side of the light-transmissive member 4 during manufacture of thelight emitting device 10. Accordingly, the light emitting surface 4 awill not be covered with the light reflecting member 5. Provided thatthe light emitting surface 4 a is covered with the light reflectingmember 5, the covered amount would be very small. Thus, high quality ofthe light emitting device 10 is obtained.

Further, the width of the frame body 5 a is smaller along the short sideof the light-transmissive member 4 than along the long side of thelight-transmissive member 4.

An exemplary size of the light reflecting member 5 is as follows. Whenthe light-transmissive member 4 has a short side measuring in a range of950 μm to 1350 μm and a long side measuring in a range of 3000 μm to6000 μm in a plan view, the width W1 of the light reflecting member 5along the short side of the light-transmissive member 4 is in a range of400 μm to 600 μm, and the width W2 of the light reflecting member 5along the long side of the light-transmissive member 4 is in a range of1000 μm to 1200 μm. Further, the difference between the width W2 of thelight reflecting member 5 along the long side of the light-transmissivemember 4 and the width W1 of the light reflecting member 5 along theshort side of the light-transmissive member 4 is in a range of 400 μm to600 μm. The width W1 of the light reflecting member 5 along the shortside of the light-transmissive member 4 is smaller than the width W2 ofthe light reflecting member 5 along the long side of thelight-transmissive member 4.

When the height from the upper surface of the base member 1 to the uppersurface of the light-transmissive member 4 is 350 μm, the height T1 ofthe frame body 5 a along the short side of the light-transmissive member4 is in a range of 150 μm to 300 μm, and preferably 210 μm; and theheight T2 of the frame body 5 a along the long side of thelight-transmissive member 4 is in a range of 200 μm to 350 μm, andpreferably 280 μm. Further, the difference between the height T2 of theframe body 5 a along the long side of the light-transmissive member 4and the height T1 of the frame body 5 a along the short side of thelight-transmissive member 4 is in a range of 50 μm to 200 μm. The heightT1 of the frame body 5 a along the short side of the light-transmissivemember 4 is smaller than the height T2 of the frame body 5 a along thelong side of the light-transmissive member 4. Further, in the presentembodiment, the height T1 of the frame body 5 a along the short side ofthe light-transmissive member 4 is higher than the height from the uppersurface of the base member 1 to the upper surfaces of the light emittingelements 3, and the height T2 of the frame body 5 a along the long sideof the light-transmissive member 4 is smaller than the height from theupper surface of the base member 1 to the upper surface of thelight-transmissive member 4.

Further, as to the size of the frame body 5 a, in a plan view, the widthof the frame body along the short side of the light-transmissive member4 is in a range of 200 μm to 400 μm, and preferably in a range of 250 μmto 300 μm. The width of the frame body 5 a along the long side of thelight-transmissive member 4 is in a range of 300 μm to 600 μm, andpreferably in a range of 350 μm to 450 μm. The width of the frame body 5a along the short side of the light-transmissive member 4 is smallerthan the width of the frame body 5 a along the long side of thelight-transmissive member 4.

The height of the upper surface (upper end) of the filling member 5 b ispreferably equal to or smaller than the height of the upper surface ofthe light-transmissive member 4. That is, the height from the basemember 1 to the upper surface of the filling member 5 b is equal to orsmaller than the maximum height from the base member 1 to the uppersurface of the light-transmissive member 4. The light output from thelight emitting surface 4 a spreads sideways also. When the upper surfaceof the light reflecting member 5 is higher than the height of the lightemitting surface 4 a, light output from the light emitting surface 4 ais reflected by the light reflecting member 5, resulting in variationsin light distribution. Accordingly, while the lateral surfaces of thelight-transmissive member 4 are covered with the light reflecting member5, a reduction in the height of the light reflecting member 5 coveringthe outer perimeter of the lateral surfaces allow the output light to bedirectly extracted outside, and thus is preferable.

In the present embodiment, as shown in FIG. 3, the filling member 5 b isslightly recessed in a cross-sectional view taken in the short sidedirection of the light-transmissive member 4. Thus, the light reflectingmember 5 is slightly recessed. The light reflecting member 5 is formedsuch that the minimum height from the base member 1 to the upper surfaceof the filling member 5 b is smaller than the maximum height of theframe body 5 a. In order to improve the front luminance of the lightemitting device 10, the upper surface of the light reflecting member 5along the long side of the light-transmissive member 4 is preferablyflush with the upper surface of the light-transmissive member 4.However, when the light reflecting member 5 is flush with thelight-transmissive member 4, the light reflecting member 5 maydisadvantageously become higher than the light emitting surface 4 a dueto thermal expansion of resin. Further, when the light reflecting member5 is deeply recessed, light may be disadvantageously leak from thelateral surfaces of the light emitting device 10. Accordingly, in thepresent embodiment, the light reflecting member 5 along the long side ofthe light-transmissive member 4 is slightly recessed in across-sectional view in the width direction. Being slightly recessedspecifically means that the height from the upper surface of the basemember 1 to the deepest portion of the recess is equal to or greaterthan the height of the frame body 5 a along the short side of thelight-transmissive member 4.

The light reflecting member 5 may be formed by a base material, whichcontains a light reflecting substance. The base material may be resinsuch as silicone resin, modified silicone resin, epoxy resin, modifiedepoxy resin, and acrylic resin, or hybrid resin containing at least onetype of the foregoing resins. The material of the light reflectingsubstance may be oxide containing one of Ti, Zr, Nb, Al, or Si, or AlN,MgF, BN or the like. Preferably, titanium oxide (TiO₂) is employed.Preferably, as the light reflecting substance, particles of which therefractive index is different from that of the base material aredispersed in the base material. The amount of light reflected ortransmitted by the light reflecting member 5 varies depending on thecontent and concentration of the light reflecting substance.Accordingly, the content and concentration of the light reflectingsubstance should be adjusted as appropriate in accordance with the shapeor size of the light emitting device 10. Per 100 parts by weight ofresin, the light reflecting substance is preferably contained by 20parts by weight to 60 parts by weight, and particularly preferablycontained by 25 parts by weight to 35 parts by weight.

The frame body 5 a and the filling member 5 b are respectively made ofhigh viscosity of a light reflecting material (i.e., resin) and lowviscosity of a light reflecting material (i.e., resin). For thematerials, the above materials of the light reflecting member 5 can beused. The viscosity of the frame body 5 a is preferably in a range of200 Pa·s to 800 Pa·s, and further preferably in a range of 350 Pa·s to450 Pa·s. The viscosity of the filling member 5 b is preferably 40 Pa·sor less, and more preferably 4 in a range of Pa·s to 8 Pa·s.

The light reflecting material of the frame body 5 a and the lightreflecting material of the filling member 5 b may be the same ordifferent from each other.

(Others)

In the present embodiment, on the base member 1, a protective element 7such as a Zener diode or the like embedded in the light reflectingmember 5 is provided via bumps 8 b.

<Operation of Light Emitting Device>

Next, a description will be given of the operation of the light emittingdevice.

In activating the light emitting device 10, current is supplied from thean external power supply to the light emitting elements 3 via theelectrically conductive patterns 2 a, 2 b, and 2 c, and the lightemitting elements 3 emit light. The light emitted from the lightemitting elements 3 is reflected by the light reflecting member 5 at theinterface between the light emitting elements 3 and the light reflectingmember 5, and at the interface between the light-transmissive member 4and the light reflecting member 5, into the light emitting elements 3and the light-transmissive member 4. In this manner, the lightpropagates through the light emitting elements 3 and thelight-transmissive member 4, and ultimately extracted to the outsidefrom the light emitting surface 4 a of the light-transmissive member 4.

<Method of Manufacturing Light Emitting Device>

Next, a description will be given of a method of manufacturing the lightemitting device according to the present embodiment.

FIGS. 5A, 5B, and 5C are diagrams schematically showing preparing a basemember in the method of manufacturing the light emitting deviceaccording to the embodiment. FIGS. 6A, 6B, and 6C are diagramsschematically showing mounting light emitting elements in the method ofmanufacturing the light emitting device according to the embodiment.FIGS. 7A, 7B, and 7C are diagrams schematically showing forming alight-transmissive member in the method of manufacturing the lightemitting device according to the embodiment. FIGS. 8A, 8B, and 8C arediagrams schematically showing forming a frame body in the method ofmanufacturing the light emitting device according to the embodiment.FIGS. 9A, 9B, and 9C are diagrams schematically showing forming afilling member in the method of manufacturing the light emitting deviceaccording to the embodiment. FIGS. 10A, 10B, and 10C are diagramsschematically showing curing a light reflecting material in the methodof manufacturing the light emitting device according to the embodiment.

FIGS. 5A, 6A, 7A, 8A, 9A, and 10A are plan views. FIGS. 5B, 6B, 7B, 8B,9B, and 10B are respectively a cross-sectional view taken along lineVB-VB in FIG. 5A, a cross-sectional view taken along line VIB-VIB inFIG. 6A, a cross-sectional view taken along line VIIB-VIIB in FIG. 7A, across-sectional view taken along line VIIIB-VIIIB in FIG. 8A, across-sectional view taken along line IXB-IXB in FIG. 9A, and across-sectional view taken along line XB-XB in FIG. 10A. FIGS. 5C, 6C,7C, 8C, 9C, and 10C are respectively a cross-sectional view taken alongline VC-VC in FIG. 5A, a cross-sectional view taken along line VIC-VICin FIG. 6A, a cross-sectional view taken along line VIIC-VIIC in FIG.7A, a cross-sectional view taken along line VIIIC-VIIIC in FIG. 8A, across-sectional view taken along line IXC-IXC in FIG. 9A, and across-sectional view taken along line XC-XC in FIG. 10A.

FIG. 11 is a schematic cross-sectional view for describing a method offorming the frame body in two stages in the forming the frame body ofthe light emitting device according to the embodiment, being an enlargedpartial cross-sectional view taken along line VIIIB-VIIIB in FIG. 8A.

The method of manufacturing the light emitting device 10 of the presentembodiment includes, as an example, preparing a base member, mountinglight emitting elements, forming a light-transmissive member, forming alight reflecting member, and curing a light reflecting material, whichare performed in order. Further, in the present embodiment, the formingthe light reflecting member includes forming a frame body, disposing anunderfill material, and forming a filling member, which are performed inthis order.

The materials, disposition and the like of the members are similar tothose described above regarding the structure of the light emittingdevice 10, and therefore the description thereof will be omitted asappropriate.

(Base Member Preparation Step)

The step of preparing a base member is an operation of preparing thebase member 1 on which a pair of positive and negative electricallyconductive patterns 2 a and 2 b, and the electrically conductiverelaying patterns 2 c are formed.

As shown in FIGS. 5A, 5B, and 5C, in the present embodiment, theelectrically conductive pattern 2 a being the cathode and theelectrically conductive pattern 2 b being the anode extend from thecenter of the base member 1 where the light emitting elements 3 aremounted toward the outer edge. Thus, external connection portionsconnected to an external power supply is structured. Further, theelectrically conductive relaying patterns 2 c are provided between theelectrically conductive patterns 2 a and 2 b. Thus, the three lightemitting elements 3 which are flip-chip mounted are connected in series.The electrically conductive patterns 2 a, 2 b, and 2 c can be formed byelectroplating, electroless plating, vapor deposition, sputtering andthe like. The through holes 6 a and 6 b can be formed by, for example,disposing a predetermined mask pattern at the time of forming theelectrically conductive patterns 2 a and 2 b.

(Light Emitting Elements Mounting Step)

The step of mounting a light emitting elements is an operation ofmounting the light emitting elements 3 on the base member 1.

As shown in FIGS. 6A, 6B, and 6C, the light emitting elements 3 and theprotective element 7 are flip-chip mounted on the electricallyconductive patterns 2 a, 2 b, and 2 c with the bumps 8 a and 8 b. Thethree light emitting elements 3 are disposed in line, and connected inseries by the electrically conductive patterns 2 a, 2 b, and 2 c on thebase member 1 as described above. In the case where a plurality of lightemitting elements 3 are mounted, preferably the light emitting elements3 are aligned and mounted substantially rectangularly as a whole in aplan view.

(Light-Transmissive Member Forming Step)

The step of forming a light-transmissive member is an operation ofcovering the upper surfaces of the light emitting elements 3 which ismounted on the base member 1, with the light-transmissive member 4 inshaped of substantially rectangular in a plan view. In the presentembodiment, the plate-like light-transmissive member 4 is provided atthe upper surfaces of the light emitting elements 3, thereby forming thelight-transmissive member 4 while avoiding the light-transmissive member4 from covering the lateral surfaces of the light emitting elements 3 atthe perimeter of the light-transmissive member 4.

As shown in FIGS. 7A, 7B, and 7C, the light-transmissive member 4 isbonded to the upper surfaces of the light emitting elements 3. The lightemitting elements 3 and the light-transmissive member 4 can be firmlybonded to each other via an adhesive agent. The adhesive agent ispreferably a material that can effectively guide the output light fromthe light emitting elements 3 toward the light-transmissive member 4side, and can optically couple the light emitting elements 3 and thelight-transmissive member 4 to each other. For example, alight-transmissive adhesive material such as silicone resin is employed.

When the light-transmissive member 4 and the light emitting elements 3are firmly bonded to each other by an adhesive agent, particularly inthe case where the light-transmissive member 4 is greater in size thanthe light emitting elements 3, the adhesive agent may be disposed toreach the lateral surfaces of the light emitting elements 3 so as tofacilitate propagation of light from the light emitting elements 3 tothe light-transmissive member 4. In this case, the adhesive agent isdisposed between the lateral surfaces of the light emitting elements 3and the light reflecting member 5. However, preferably the adhesiveagent is not disposed outer than the area immediately under thelight-transmissive member 4. Thus, the light is properly reflected andpropagated between the light emitting elements 3 and the lightreflecting member 5, and occurrence of color non-uniformity can beprevented. Further, the light emitting elements 3 and thelight-transmissive member 4 can be firmly bonded to each other by directbonding through compression bonding, sintering, surface-activatedbonding, atomic diffusion bonding, and hydroxyl group bonding.

(Light Reflecting Member Forming Step)

The step of forming a light reflecting member is an operation of formingthe light reflecting member 5 which has a substantially rectangularframe shape in a plan view. In the forming the light reflecting member,the light reflecting member 5 is formed such that the width of the lightreflecting member 5 is smaller along the short side of thelight-transmissive member 4 than along the long side of thelight-transmissive member 4.

The forming the light reflecting member includes forming a frame body,disposing an underfill material, and forming a filling member.

[Frame Body Forming Step]

The step of forming a frame body is an operation of forming the framebody 5 a to surround the light-transmissive member 4.

As shown in FIGS. 8A, 8B, and 8C, in the forming the frame body, theframe body 5 a is formed such that the frame body 5 a is nearer to thelight-transmissive member 4 along the short side of thelight-transmissive member 4 than along the long side of thelight-transmissive member 4. That is, in FIG. 2, the frame body 5 a isformed such that the distance W1 from the left side of thelight-transmissive member 4 to the left side of the frame body 5 a, andthe distance W1 from the right side of the light-transmissive member 4to the right side of the frame body 5 a are smaller than the distance W2from the upper side of the light-transmissive member 4 to the upper sideof the frame body 5 a, and the distance W2 from the lower side of thelight-transmissive member 4 to the lower side of the frame body 5 a.

Further, in the forming the frame body, the frame body 5 a is formedsuch that the height of the frame body 5 a is smaller along the shortside of the light-transmissive member 4 than along the long side of thelight-transmissive member 4. That is, as shown in FIGS. 3 and 4, theframe body 5 a is formed such that the distance T1 from the base member1 to the upper end of the frame body 5 a along the short side of thelight-transmissive member 4 is smaller than the distance T2 from thebase member 1 to the upper end of the frame body 5 a along the long sideof the light-transmissive member 4.

After the space between the frame body 5 a and the light-transmissivemember 4 is filled with resin constituting the filling member 5 b, resindepression takes place, that is, the resin is drawn toward the basemember 1 side. While the resin depression is strong between the framebody 5 a along the long side of the light-transmissive member 4 and thelight-transmissive member 4, the resin depression is weak between theframe body 5 a along the short side of the light-transmissive member 4and the light-transmissive member 4 because of the small distancebetween them. Accordingly, when the height of the frame body 5 a alongthe short side of the light-transmissive member 4 is similar to theheight of the frame body 5 a along the long side of thelight-transmissive member 4, the resin may disadvantageously creep uponto the light emitting surface 4 a along the short side of thelight-transmissive member 4 when the space is filled with the resin. Incontrast, as in the light emitting device 10 of the present embodiment,the frame body 5 a can be formed such that the height T1 of the framebody 5 a along the short side of the light-transmissive member 4 issmaller than the height T2 of the frame body 5 a along the long side ofthe light-transmissive member 4. This makes the resin less likely tocreep up onto the light emitting surface 4 a.

Setting the height T1 of the frame body 5 a to be smaller than theheight T2 thereof helps the filling member 5 b avoid creeping up ontothe light emitting surface 4 a and reduces the amount of the resinconstituting the light reflecting member 5. Hence, the light reflectingmember 5 is less susceptible to deterioration.

As shown in FIG. 11, in the forming the frame body, preferably the framebody 5 a is formed by: forming a first frame body 50 by applying thelight reflecting material (resin) to surround the light-transmissivemember 4; and thereafter forming a second frame body 51 by furtherapplying the light reflecting material (resin) on the first frame body50. The light reflecting material is applied for two successive roundsto be overlaid in the height direction outside the perimeter of thelight-transmissive member 4. Thus, the frame body 5 a having a two-stagestructure is formed. In this manner, the frame body 5 a having a smallwidth and a relatively great height can be obtained.

Depending on the viscosity of the resin of the frame body 5 a, the resinis required by a greater amount in order to reliably obtain a desiredheight. This invites an increase in the width. In view of massproductivity of the light emitting device 10, in order to reliablyobtain the desired height of the frame body 5 a while reducing itswidth, the resin is preferably discharged for a plurality of successiverounds outside the perimeter of the light-transmissive member 4 toattain the desired height.

The frame body 5 a made of resin having a two-stage structure can beformed by: applying resin constituting the first frame body 50; andthereafter, before curing the applied resin, applying resin constitutingthe second frame body 51 on the first frame body 50. Further, the framebody 5 a made of resin having a two-stage structure can be formed by,for example: using a discharging apparatus as described below, applyingresin of the first frame body 50; and successively to the applying,applying resin of the second frame body 51 on the first frame body 50 soas not to break discharge of the resin from the discharging apparatus informing the first frame body 50 and the second frame body 51.

The frame body 5 a can be formed by, for example, using a dischargingapparatus (i.e., resin discharging apparatus) that can continuouslydischarge liquid resin by air pressure (see Japanese Unexamined PatentApplication Publication No. 2009-182307).

In use of the discharging apparatus, the shifting speed of a needle ofthe discharging apparatus is set to be faster along the short side ofthe light-transmissive member 4 than along the long side of thelight-transmissive member 4. Thus, while the discharge flow rate ofresin discharged from the discharging apparatus is kept constant, theheight of the frame body 5 a can be set to be smaller along the shortside of the light-transmissive member 4 than along the long side of thelight-transmissive member 4. Further, changing the speed in this mannerallows the width of the frame body 5 a to be smaller along the shortside of the light-transmissive member 4 than along the long side of thelight-transmissive member 4, despite the diameter of the needle of thedischarging apparatus being kept constant. By virtue of the reducedwidth of the frame body 5 a along the short side of thelight-transmissive member 4, the width of the light reflecting member 5is reduced and a space between the light-transmissive member 4 and theframe body 5 a is reliably obtained. This facilitates filling the spacebetween the light-transmissive member 4 and the frame body 5 a along theshort side of the light-transmissive member 4 with resin.

For example, without being limited to adjusting the speed, adjusting thedischarge flow rate enables forming the substantially rectangular framebody 5 a of which height differs between along the long side of thelight-transmissive member 4 and along the short side thereof. However,in forming the substantially rectangular frame body 5 a, irrespective ofthe intention to change the height along each side, the shifting speedof the needle changes due to the needle changing the shifting directionaround a corner of the rectangle. Accordingly, when it is desired toachieve different heights between along the long side and the short sideby the discharge flow rate, a change in the speed due to a change in theshifting direction of the needle and switching of the discharge flowrate must be in synchronization with each other. Otherwise, the shape ofthe resin frame would not be stabilized. However, in the method ofmanufacturing the light emitting device 10 according to the presentembodiment, needle shifting speed is switched at a timing when the speedis changed in association with change of the shifting direction. Thus,the frame body 5 a having different heights can be formed with simpleoperations, which is suitable for volume production.

The frame body 5 a is preferably formed such that the height along thelong side of the light-transmissive member 4 is substantially equal toor smaller than the height of the upper surface of thelight-transmissive member 4 serving as the light emitting surface 4 a.Such forming enables use of creeping of resin, which structures thefilling member 5 b formed in the later step, and cause the resin tocover the lateral surfaces of the light emitting elements 3 and those ofthe light-transmissive member 4, while reducing the creeping up of theresin onto the upper surface of the light-transmissive member 4 andobstructing the light output. Further, making the frame body 5 a greaterin height requires an increased amount of resin and results in a greaterwidth. In view of the foregoing also, preferably, the height of theframe body 5 a is substantially equal to or smaller than the height ofthe upper surface of the light-transmissive member 4. Further, theheight of the frame body 5 a along the long side of thelight-transmissive member 4 is raised enough to prevent the resincovering the lateral surfaces of the light emitting elements 3 and thoseof the light-transmissive member 4 from overflowing. Preferably, theheight of the frame body 5 a along the long side of thelight-transmissive member 4 is half the height from the surface of thebase member 1 or from the electrically conductive patterns 2 a and 2 bto the light emitting surface 4 a or greater.

Further, increased viscosity of the frame body 5 a can suppress anincrease in the width while raising the height, and improves thedimensional precision. However, high viscosity of resin lowers thedischarging speed and thus reduces productivity, and reduces adhesionbetween the frame body 5 a and the base member. In particular, when theframe body 5 a is formed using a discharging apparatus that dischargesliquid resin, the frame is formed by overlaying the starting point ofthe discharged resin and the end point thereof. Here, high-viscosityresin may have disadvantageous effects that space is generated at theoverlaid portion, or the adhesion strength of the discharged resinbetween the start point and the end point may varies. The viscosity ofthe frame body 5 a may be just enough to provide, for example, the framebody 5 a with a semicircular cross section, with its tail wetlyspreading over the base member 1. For forming such a frame body,preferably resin of which viscosity is about 200 to 800 Pa s is employedfor the frame body 5 a.

[Underfill Material Disposing Step]

As in the present embodiment, when the light emitting elements 3 areflip-chip mounted on the electrically conductive patterns (e.g., metalplating) formed on the base member 1 via the electrically conductivemembers such as the bumps, preferably an underfill material is disposedin the space between the portion of the base member 1 where the lightemitting elements 3 are mounted and the light emitting elements 3. Thedisposed underfill material can absorb the stress due to the differencebetween the light emitting elements 3 and the base member 1 in thethermal expansion rate, and improve the heat dissipation property.Employing a light reflecting member such as white-color resin as theunderfill material, light output from the light emitting elements 3toward a direction of the base member 1 can be reflected, and theluminous flux can be increased.

[Filling Member Forming Step]

The step of forming a filling member is an operation of providing thefilling member 5 b that covers the lateral surfaces of thelight-transmissive member 4 between the frame body 5 a and thelight-transmissive member 4.

As shown in FIGS. 9A, 9B, and 9C, before curing the frame body 5 a, thespace inside the frame body 5 a is filled with a light reflectingmaterial (resin) that structures the filling member 5 b. In the presentembodiment, the filling member 5 b covers the lateral surfaces of thelight emitting elements 3 and those of the light-transmissive member 4.The upper surface of the light-transmissive member 4 exposed outside thefilling member 5 b serves as the light emitting surface 4 a of the lightemitting device 10. Further, the height of the upper surface (i.e.,upper end) of the filling member 5 b is set to be equal to or smallerthan the height of the upper surface of the light-transmissive member 4.

The amount of the resin constituting the filling member 5 b is adjustedto be enough to cover the lateral surfaces of the light emittingelements 3 and those of the light-transmissive member 4. While itdepends on the surface state of the members or the viscosity of theresin, the height of the filling member 5 b is, for example, half theheight from the surface of the base member 1 or the electricallyconductive patterns 2 a and 2 b to the light emitting surface 4 a orgreater. In order to prevent leakage of light, the filling member 5 bpreferably has a great thickness particularly at the lateral surfaces ofthe light emitting elements 3 which are the light emission sources.Accordingly, preferably the frame body 5 a is formed to be at leasthigher than the upper surfaces of the light emitting elements 3, and theamount of the resin constituting the filling member 5 b is adjusted suchthat the lowest portion in the surface of the filling member 5 b becomeshigher than the upper surfaces of the light emitting elements 3.

Further, in providing the resin constituting the filling member 5 b, thespace between the frame body 5 a along the short side of thelight-transmissive member 4 and the light-transmissive member 4 may bedirectly filled with the resin. However, filling the space between theframe body 5 a along the long side of the light-transmissive member 4and the light-transmissive member 4 with the resin allows the resin torun through the space between the frame body 5 a along the short side ofthe light-transmissive member 4 and the light-transmissive member 4.This eliminates the necessity of elaborately filling the narrow spacebetween the frame body 5 a along the short side of thelight-transmissive member 4 and the light-transmissive member 4 with theresin, simplifying the manufacture of the light emitting device 10.

Further, the protective element 7 is completely covered with the fillingmember 5 b in order to prevent the protective element 7 from absorbinglight. Here, preferably the frame body 5 a and the filling member 5 bcover the portions where the pair of positive and negative electricallyconductive patterns 2 a and 2 b oppose to each other, such as near thelight emitting elements 3 or near the protective element 7. Thisprevents short-circuiting due to dust attached thereto.

In order for the lateral surfaces of the light emitting elements 3 andthose of the light-transmissive member 4 to be surely covered with theresin, the light reflecting material (resin) constituting the frame body5 a is preferably higher in the viscosity than the light reflectingmaterial (resin) constituting the filling member 5 b.

When the resin constituting the frame body 5 a is higher in theviscosity than the resin constituting the filling member 5 b, ascompared to the case where the light reflecting member 5 is structuredsingularly by resin of high viscosity, the resin easily creeps up alongthe lateral surfaces of the light emitting elements 3 or those of thelight-transmissive member 4. Accordingly, the lateral surfaces of thelight emitting elements 3 and those of the light-transmissive member 4can be covered with ease. Further, when the light reflecting member 5 isstructured singularly by resin of low viscosity, the tail of the resinexcessively spreads, whereby the light emitting device 10 is increasedin size. Here, use of a mold for stopping the resin from excessivelyspreading, removal of the mold may pull the resin, and the resin may beseparated from the base member 1. Accordingly, in the presentembodiment, the frame body 5 a is made of high viscosity resin, and thefilling member 5 b is made of low viscosity resin. Being made of resinhigher in the viscosity than the resin constituting the filling member 5b, even before curing, the frame body 5 a can function as a dam thatblocks a flow of the low viscosity resin constituting the filling member5 b. The viscosity can be adjusted by, for example, the viscosity of theresin itself being the base material. In this case, the same lightreflecting substance may be contained in the base material of the framebody 5 a and in the base material of the filling member 5 b.

(Light Reflecting Material Curing Step)

The step of curing a light reflecting material is an operation of curingthe resin constituting the frame body 5 a and the resin constituting thefilling member 5 b as shown in FIGS. 10A, 10B, and 10C, which isperformed after the filling the space with the resin constituting thefilling member 5 b. Since the frame body 5 a and the filling member 5 bare formed on the identical base member 1 as being tightly bonded toeach other, the resins can be cured in the same operation. Specifically,after providing the resin constituting the frame body 5 a, the resin istentatively cured; and after filling the space with the resinconstituting the filling member 5 b, the resin constituting the framebody 5 a and the resin constituting the filling member 5 b are fullycured together. As used herein, to tentatively cure means to cure theresin to the state where the resin keep its shape without flowing. Thus,the frame body 5 a and the filling member 5 b are rigidly bonded to eachother, and so integrated with each other that the interface therebetweenis hardly recognizable. This improves the adhesion force between theframe body 5 a and the filling member 5 b, and reduces separation of theframe body 5 a and the filling member 5 b from each other. Thus, thelight emitting device 10 with improved reliability can be obtained.Preferably, in order for the resin constituting the frame body 5 a andthe resin constituting the filling member 5 b to be cured underidentical conditions, the resins as the base materials are substantiallyidentical to each other in the curing conditions.

With the light emitting device 10 of the present embodiment, asdescribed above, light leakage from the lateral surfaces of thelight-transmissive member 4 less likely to occur, and exhibition of highfront luminance can be realized. Additionally, with the reduced amountof the resin member which tends to deteriorate, the light reflectingmember of the light emitting device 10 is less susceptible todeterioration.

In general, when a light reflecting member is repeatedly exposed tothermal shock, thermal stress may disadvantageously cause separation atthe interface between the light reflecting member and members nearby,for example, at the interface between the light reflecting member and abase member, or at the interface between the light reflecting member anda light-transmissive member. However, in the light emitting device 10 ofthe present embodiment, the width of the light reflecting member 5 issmaller along the short side of the light-transmissive member 4 thanalong the long side of the light-transmissive member 4. This reduces thethermal stress at the interface between the light reflecting member 5and the light-transmissive member 4, and the thermal stress at theinterface between the light reflecting member 5 and the base member 1.Consequently, in the light emitting device 10 according to the presentembodiment, separation at the interface between the light reflectingmember 5 and the members nearby less likely to occur.

As to the shape of the light emitting device 10 according to the presentembodiment, when the width of the light reflecting member 5 along theshort side of the light-transmissive member 4 is the same as the widthof the light reflecting member 5 along the long side of thelight-transmissive member 4 (that is, being wide along both sides), thethermal stress at the interface between the light reflecting member 5and the light-transmissive member 4 becomes greater. Further, when thewidth of the light reflecting member 5 along the long side of thelight-transmissive member 4 is the same as the width of the lightreflecting member 5 along the short side of the light-transmissivemember 4 (that is, being narrow along both sides), the thermal stress atthe interface between the light reflecting member 5 and the base member1 becomes greater. Further, when the width of the light reflectingmember 5 along the short side of the light-transmissive member 4 isgreater than the width of the light reflecting member 5 along the longside of the light-transmissive member 4, the thermal stress at theinterface between the light reflecting member 5 and thelight-transmissive member 4, and the thermal stress at the interfacebetween the light reflecting member 5 and the base member 1 becomegreater.

As described above, the light emitting device 10 according to thepresent embodiment and the method of manufacturing the same can attainthe objective of providing a light emitting device including a lightreflecting member that is less susceptible to deterioration and a methodof manufacturing the same. Further, the light emitting device 10according to the present embodiment and the method of manufacturing thesame can attain the objective of providing a light emitting device inwhich separation at the interfaces between a light reflecting member andmembers nearby less likely to occurs and a method of manufacturing thesame.

Further, since the light emitting device 10 according to the presentembodiment requires a reduced amount of resin, the amount of gas that isreleased in curing the resin can be reduced. Thus, the risk of anyorganic material attaching to the product can be reduced.

The method of manufacturing the light emitting device 10 according tothe present embodiment enables the frame body 5 a to be formed in asimple manner through use of a discharging apparatus. This increasesvolume productivity of the light emitting device 10. Use of asmall-diameter needle in forming the frame body 5 a reduces outerdimensional tolerances of the corners of the frame body 5 a. Further,use of a small-diameter needle in forming the frame body 5 a cansuppress the resin at the corners of the frame body 5 a from spreading,and sharp corners of the frame body 5 a can be formed. Use of agreat-diameter needle in forming the frame body 5 a provides fourcorners of the frame body 5 a being rounded. On the other hand, use of asmall-diameter needle allows the four corners of the frame body 5 a tohave right angles, and the outer dimension of the corners is morestabilized. A small-diameter needle refers to a needle of which innerdiameter at the resin discharging port is 30 μm to 200 μm. In the methodof manufacturing the light emitting device 10 according to the presentembodiment, the frame body 5 a is formed using a discharging apparatushaving a small-diameter needle of which inner diameter is about 100 μm.

Since the method of manufacturing the light emitting device 10 accordingto the present embodiment provides the light reflecting member 5 with asmall width not along every side, the space between the frame body 5 aand the light-transmissive member 4 can be easily filled with resin.

In the foregoing, the light emitting device according to the presentdisclosure and the method of manufacturing the same have beenspecifically described based on the embodiment, the spirit of thepresent disclosure is not limited thereto and should be construedbroadly based on the scope of claims. It goes without saying that thespirit of the present invention includes also variations andmodifications based on the description.

For example, in the embodiment described above, the plate-likelight-transmissive member 4 is bonded to the upper surfaces of the lightemitting elements 3 and the lateral surfaces of the light emittingelements 3 are directly covered with the light reflecting member 5.However, the lateral surfaces of the light emitting elements 3 may becovered with the light-transmissive member 4. That is, thelight-transmissive member 4 may cover the lateral surfaces of the lightemitting elements 3 at the perimeter of the light-transmissive member 4,and the light reflecting member 5 may cover the lateral surfaces of thelight-transmissive member 4 provided at the lateral surfaces of thelight emitting elements 3.

In the embodiment described above, the lateral surfaces of thelight-transmissive member 4 extend out from the portion at which thelateral surfaces of the light emitting elements 3 is located in across-sectional view. Alternatively, the lateral surfaces of thelight-transmissive member 4 and the lateral surfaces of the lightemitting elements 3 may be at the same position, and to be flush witheach other. In this structure, the lateral surfaces of thelight-transmissive member 4 and the lateral surfaces of the lightemitting elements 3 are easily covered with the light reflecting member5.

In the embodiment described above, the light-transmissive member 4 as asingle light-transmissive member 4 is integrally provided at the uppersurfaces of the three light emitting elements 3. Alternatively,light-transmissive members may be respectively joined to the lightemitting elements 3, and the light-transmissive members may servecollectively as one substantially rectangular light-transmissive memberin a plan view.

In the embodiment described above, the light-transmissive member 4 has ashape of a plate of which upper surface and lower surface aresubstantially in parallel to each other. Alternatively, thelight-transmissive member 4 has surfaces with projections andrecessions, or a curved surface. For example, the light-transmissivemember 4 may be lens-shaped, and the lateral surfaces of the lens-shapedlight-transmissive member 4 may be covered with the light reflectingmember 5. This structure improves the light output efficiency.

In the embodiment described above, three light emitting elements 3 aremounted on the base member 1. However, the number of the light emittingelements 3 mounted is not limited thereto. At least one light emittingelement 3 mounted suffices. The number may be changed as appropriatedepending on the size of the desired light emitting device 10 and therequired luminance. In the case where four or more light emittingelements 3 are mounted, they may be arranged in line, or may be arrangedin array.

In the embodiment described above, the light emitting elements 3 areflip-chip mounted on the base member 1, however they may be face-upmounted.

In the embodiment described above, the frame body 5 a is formed suchthat its outer edge is a rectangular frame shape with rounded corners ina plan view, however the frame body 5 a may be rectangular with its fourcorners each forming a right angle in a plan view.

Still further, in the manufacturing method according to the embodimentdescribed above, the forming a frame body, and thereafter the disposingan underfill material is performed. However, the forming a frame bodymay be performed after the disposing an underfill material so long asthe underfill material can be disposed at the position within the areaof the frame body 5 a.

What is claimed is:
 1. A light emitting device comprising: a basemember; a light emitting element mounted on the base member; alight-transmissive member that covers an upper surface of the lightemitting element, and is substantially rectangular in a plan view; and alight reflecting member that covers a lateral surface of thelight-transmissive member, the light reflecting member having asubstantially rectangular frame shape in a plan view, wherein a width ofthe light reflecting member is smaller along a short side of thelight-transmissive member than along a long side of thelight-transmissive member, and wherein a height of the light reflectingmember is smaller along the short side of the light-transmissive memberthan along the long side of the light-transmissive member at a positionseparated from an outer edge of the light reflecting member by apredetermined distance.
 2. A light emitting device comprising: a basemember; a light emitting element mounted on the base member; alight-transmissive member that covers an upper surface of the lightemitting element, and is substantially rectangular in a plan view; and alight reflecting member that includes a frame body that surrounds thelight-transmissive member, and a filling member disposed between theframe body and the light-transmissive member so as to cover a lateralsurface of the light-transmissive member, the light reflecting memberhaving a substantially rectangular frame shape in a plan view, wherein aheight of the frame body is smaller along a short side of thelight-transmissive member than along a long side of thelight-transmissive member.
 3. The light emitting device according toclaim 2, wherein the height of the frame body is greater than a heightfrom an upper surface of the base member to the upper surface of thelight emitting element, and smaller than a height from the upper surfaceof the base member to an upper surface of the light-transmissive member.4. The light emitting device according to claim 2, wherein a width ofthe light reflecting member is smaller along the short side of thelight-transmissive member than along the long side of thelight-transmissive member in a plan view.
 5. The light emitting deviceaccording to claim 2, wherein a height of an upper surface of thefilling member is equal to or smaller than a height of an upper surfaceof the light-transmissive member from an upper surface of the basemember.
 6. The light emitting device according to claim 2, wherein awidth of the frame body is smaller along the short side of thelight-transmissive member than along the long side of thelight-transmissive member.
 7. The light emitting device according toclaim 2, wherein, at a perimeter of the light-transmissive member, thelight reflecting member covers a lateral surface of the light emittingelement.
 8. The light emitting device according to claim 2, wherein thelight-transmissive member contains a fluorescent material.
 9. The lightemitting device according to claim 2, wherein the light-transmissivemember has a plate-like shape.
 10. The light emitting device accordingto claim 2 comprising a plurality of the light emitting elements.